linux-kernel - Re: [PATCH v10 10/26] KVM: s390: interfaces to clear CRYCB masks

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Date:   Mon, 24 Sep 2018 13:01:53 +0200
From:   Cornelia Huck <cohuck@...hat.com>
To:     Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...ibm.com,
        kwankhede@...dia.com, bjsdjshi@...ux.vnet.ibm.com,
        pbonzini@...hat.com, alex.williamson@...hat.com,
        pmorel@...ux.vnet.ibm.com, alifm@...ux.vnet.ibm.com,
        mjrosato@...ux.vnet.ibm.com, jjherne@...ux.vnet.ibm.com,
        thuth@...hat.com, pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
        frankja@...ux.ibm.com, Tony Krowiak <akrowiak@...ux.ibm.com>
Subject: Re: [PATCH v10 10/26] KVM: s390: interfaces to clear CRYCB masks

On Wed, 12 Sep 2018 15:43:00 -0400
Tony Krowiak <akrowiak@...ux.vnet.ibm.com> wrote:

> From: Tony Krowiak <akrowiak@...ux.ibm.com>
> 
> Introduces two new KVM interface to clear the APM, AQM and ADM masks in
> the guest's CRYCB.  The VCPUs are taken out of SIE to ensure the VCPUs do
> not get out of sync.

Hm, that patch description does not quite match what the patch actually
does...

> 
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> Acked-by: Halil Pasic <pasic@...ux.ibm.com>
> Tested-by: Michael Mueller <mimu@...ux.ibm.com>
> Tested-by: Farhan Ali <alifm@...ux.ibm.com>
> Tested-by: Pierre Morel <pmorel@...ux.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h |    2 ++
>  arch/s390/kvm/kvm-s390.c         |   15 +++++++++++++++
>  2 files changed, 17 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 423cce7..1e758fe 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -858,6 +858,8 @@ void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
>  void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
>  				 struct kvm_async_pf *work);
>  
> +void kvm_arch_crypto_clear_masks(struct kvm *kvm);
> +
>  extern int sie64a(struct kvm_s390_sie_block *, u64 *);
>  extern char sie_exit;
>  
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d717041..ac4c93f 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2033,6 +2033,21 @@ static void kvm_s390_set_crycb_format(struct kvm *kvm)
>  		kvm->arch.crypto.crycbd |= CRYCB_FORMAT1;
>  }
>  
> +void kvm_arch_crypto_clear_masks(struct kvm *kvm)
> +{
> +	mutex_lock(&kvm->lock);
> +	kvm_s390_vcpu_block_all(kvm);
> +
> +	memset(&kvm->arch.crypto.crycb->apcb0, 0,
> +	       sizeof(kvm->arch.crypto.crycb->apcb0));
> +	memset(&kvm->arch.crypto.crycb->apcb1, 0,
> +	       sizeof(kvm->arch.crypto.crycb->apcb1));
> +
> +	kvm_s390_vcpu_unblock_all(kvm);
> +	mutex_unlock(&kvm->lock);
> +}
> +EXPORT_SYMBOL_GPL(kvm_arch_crypto_clear_masks);

...although this function looks fine.

> +
>  static u64 kvm_s390_get_initial_cpuid(void)
>  {
>  	struct cpuid cpuid;